Bearing component part and a method to form a bearing component

ABSTRACT

A bearing component part for use in a diffusion welding process, comprising a core part presenting a first circumferential surface, at least one annular part presenting a second circumferential surface, wherein the core part and the annular part are attached to and along each other in a circumferential manner through their first circumferential surface and second circumferential surface. The at least one annular part is substantially u-shaped in a cross sectional view, comprising two opposing sides connected by a base side together forming a space. The at least one annular part is arranged to receive a first material in the space formed by the u-shape.

CROSS REFERENCE TO RELATED APPLICATION

This is a United States National Stage Application claiming the benefitof International Application Number PCT/SE2014/000042 filed on 7 Apr.2014 (07.04.2014), which claims the benefit of Sweden (SE) PatentApplication 1300270-4 filed on 12 Apr. 2013 (12.04.2013), both of whichare incorporated herein by reference in their entireties.

TECHNICAL FIELD

According to a first aspect, the invention presents a bearing componentpart, such as a part to an outer ring, an inner ring or a roller of aroller bearing.

According to a second aspect, the invention presents a forming method ofa bearing component using the part according to the first aspect of theinvention.

According to a third aspect, the invention presents a bearing componentformed by using the bearing component part according to the first aspectof the invention.

BACKGROUND OF THE INVENTION

Rolling bearings are well known and comprise roller bearings, ballbearings and also combinations thereof. In recent years an increaseddifferentiation of customers' needs and demands has been seen. This hasresulted in an increase in customization of rolling bearings, which inturn has lead to that more variants and smaller batches of each variantis manufactured. This development has especially been seen for largerrolling bearings, such as larger spherical roller bearings, taperedroller bearings, cylindrical roller bearings etc. Also, larger rollingbearings are often manufactured in smaller series since these bearingsoften are manufactured on direct customer orders and are notmanufactured and put on stock. The different customer demands relate toe.g. different material demands, different demands on material hardness,wear characteristics, ductility, heat resistance etc. In addition, thehigher customer demands often relate to a need to customize and optimizethe rolling contact surfaces between the bearing components. Therefore,there is a need to find a cost effective solution that could increasethe ability to offer different customized solutions for customers withdifferent needs and to be able to fulfill the high and increasingdemands on improved rolling contact surfaces.

SUMMARY OF THE INVENTION

An object of the invention is to provide a solution to the aboveidentified needs.

According to the first aspect of the invention, the object has beenachieved by providing a bearing component part for use in a diffusionwelding process. The bearing component part for use in a diffusionwelding process comprises a core part presenting a first circumferentialsurface and at least one annular part presenting a secondcircumferential surface. The core part and the annular part are attachedto and along each other in a circumferential manner through their firstand second circumferential surfaces. The at least one annular part issubstantially u-shaped in a cross sectional view, comprising twoopposing sides connected by a base side together forming a space,wherein the at least one annular part is arranged to receive a firstmaterial in the space formed by the u-shape. By providing the bearingcomponent part having this substantially u-shaped annular part, theforming method becomes easier since the first material to join to thecore part is conveniently collected and located against the surface towhere it is supposed to join. There can also be several u-shaped annularparts attached to the circumferential surface when it is not desired tojoin a first material to the full circumferential surface, but only toparts of it, such as when joining several ornaments, such as flangesetc. By providing this bearing component part, the overall process offorming a bearing component is simplified, since the u-shaped annularpart is already attached to the core part ready to fill with the firstmaterial and is easy to handle. The quality in terms of tolerances canbe assured early in the process. The bearing component part, often aless critical component when it comes to the performance of the finalbearing, can be outsourced to a supplier. Later the bearing componentpart can be used by the company making the final bearing componentaccording to the specific product specification from customers, forinstance by adding the required first material in the space of theu-shape and perform the final machining/forming of the end shape.Further by having the u-shaped annular part attached to the side wherethe first material supposed to be applied enables less material of theexpensive qualitative material can be used, in comparison to forinstance lowering the bearing component in a capsule to gather the firstmaterial all around component to be joined.

The annular part is substantially u-shaped in a cross-sectional view. Bysubstantially u-shaped is also meant that there can be additionalfeatures to it to follow the end shape of the final bearing component.For spherical surfaces, such as in spherical roller bearings (SRB) or atoroidal bearing the u-shape would be bent along the spherical shape forinstance. For a deep groove ball bearing (DGBB) one of the sides in theu-shape could have a groove shaped feature to form the raceway groove.For a tapered roller bearing the u-shape could actually be more in theshape of a V. Also the u-shaped part can have additional features in theshape to form additional portions to the end component, such as flangesetc.

By axial direction is meant the direction in line with the envisionedshaft the bearing is supposed to be connected to. By radial direction ismeant the direction perpendicularly from the center of the envisionedshaft. Thus by the cross-sectional view of the annular part is meant thesurface made in the axial direction of the shaft and out in radialdirection, thus the surface of the cross sectional view will cross thecenter of the shaft along its axial length.

In an embodiment of the bearing component part the secondcircumferential surface of the annular part being connected to the corepart is one of the opposing sides of the u-shape. The attachmentprocedure can be performed by welding, using hot components, using ageometrical fit and a heat difference to join components, by gluing,mechanical fastening or any other method known to the person skilled inthe art. Surfaces may need to be cleaned and mechanically or chemicallyactivated to improve the bond between the materials. An additionalmethod could be to plastically deform the material by a rolling process.This process may be done in parallel to a local surface heating process.The u-shape can be explained having a base side connecting two opposingsides stretching in parallel perpendicularly from the base side. Forinstance when the joined first material will comprise a radial racewayof the ring of the final bearing component, the bearing component partwill have the u-shaped circular part attached like this so that the ringcan be laid down horizontally and the opening of the u-shaped circularpart is directed upwards so that the material to join can be filled inthe space made my the u-shaped circular part and contained there by theforce of gravity. If it is an inner ring the u-shaped circular part willbe joined on its radially inner opposing side on to the ring's radiallyouter circumferential surface. The same principle applies if it is theouter surface of a roller that shall be formed. If it is an outer ringthe u-shaped circular part will be joined on its radially outer opposingside onto the ring's radially inner circumferential surface.

In an embodiment of the bearing component part, the secondcircumferential surface of the annular part being connected to the corepart is the base side of the u-shape. This can for instance bebeneficial when joining a surface of an axial thrust bearing, so thatthe material can be put onto the surface and kept there by the force ofgravity.

In an embodiment of the bearing component part, the annular part is alow carbon steel. In a further embodiment the low carbon steel has acarbon content of less than 0.3 weight % (wt %), but it could easily beas low 0.05 wt % and as high as 0.6 wt %. In another embodiment the lowcarbon steel is a ferritic steel. By having a material with very lowcarbon content, the material will attract carbon from both the first andthe second material, slowly evening out the differences in carboncontent between the first and second material, since the carbon contentof both the first and second material is higher than the low ferriticsteel. This way the process is controlled so that no weak and brittlecementite or other unwanted complex carbides are created, and thestrength of the transition zone is further ensured. In anotherembodiment of the method, the annular part is a sheet metal. This way itcan easily be formed to encapsulate and abut the core part. In yetanother embodiment of the method the thickness of the annular part is0.5-10 mm thick. The thickness is selected in relation to processtemperature and time in such way that the material which will besubjected to the highest stress is neither carbon enriched norsignificantly carbon depleted. The core material is allowed to beslightly depleted in carbon while the annular part material is enrichedwith carbon allowing it to be at least partly having a martensiticstructure in a following hardening operation. In another embodiment theannular part also contains nitrogen. This is to prevent nitrogen fromdiffusing from the material to be filled into u-shaped annular part thatwill constitute the high load and endurance part, since the nitrogendiffusion from this material could affect its material propertiesnegatively. In a further embodiment several annular parts are put on thecore part in order to allow for the carbon to diffuse in a controlledand optimum manner.

In an embodiment of the bearing component part, the core part is a castiron. In a further embodiment the core part is a cast iron with a carboncontent of at least 2%. A cast iron typically contains between 2.1-4 wt% carbon. In yet another embodiment of the method the core part is acast steel. In a further embodiment the core part is a cast steel with acarbon content of 0.5 wt % or less, but it could be as much as 2 wt %.These materials are often cheaper than high cleanliness steels, thuspreferably the main part of the component can be made by cast iron orcast steel, after which the more expensive high cleanliness steel can beapplied at the most critical areas that requires it. In anotherembodiment this cast iron/steel core part of is formed by casting. Thisis cheaper than other traditional forming methods, but it could ofcourse also be made by rolling or forging or any other warm or coldworking method. This part may be the main part of a bearing component,for instance in the case of a bearing it could be the central part of aroller, or the ring part that does not constitute the part enduringheavy load, such as the raceway or flange.

According to the second aspect of the invention, the object has beenachieved by providing a method to form a bearing component by means ofdiffusion welding. The method comprises the steps of first providing abearing component part as described according to the first aspect of theinvention where a first material is placed in the space formed by theu-shaped annular part. Then the space formed by the u-shaped annularpart is sealed creating a closed space, after which the diffusionwelding process is performed. By providing the bearing component parthaving this substantially u-shaped annular part, the forming methodbecomes easier since the material to join to the core part isconveniently collected and located against the surface to where it issupposed to join. The u-shaped annular part also functions as anintermediate material between the core part and the first material to bejoined. When forming high quality components that need to endure highloads during a long period of time, such as bearings or pressing toolsetc, known methods to join two materials by diffusion welding or hotisostatic pressing are sensitive to generate weak zones in thetransition zone where the materials join each other. There may be acarbon potential between the materials, i.e. one of the two joinedmaterials may gain carbon in the joining process while the othermaterial may lose carbon. A carbon potential is explained by the abilityof an environment containing active carbon to alter or maintain, underprescribed conditions, the carbon level of a steel. In any particularenvironment, the carbon level attained will depend on such factors astemperature, time and steel composition. Carbon potential is thus adifference in carbon activity between e.g. two materials. Thus if thereis a difference in carbon activity, i.e. when the carbon potential isnot zero, the carbon will diffuse from one material to the other. Thecarbon gradients in the two materials may result in weak and brittlephases during a subsequent heat treatment. A transition zone with largerfraction of weaker brittle microstructure phases such as cementitenetworks or complex metal carbides may significantly reduce the strengthof any or both of the two joined materials. By selecting the alloyingcontent of the two joining materials and/or adopting the processtemperature the diffusion rate of carbon between the materials can bereduced. The hardening properties of both alloys are then to a largeextent preserved and the volumes surrounding the transition zone willnot have large volume of weak or brittle phases. The two materials keepits ability and microstructure all the way to the transition zone. Thesize of the transition zone is reduced and the potential problems ofmaterial brittleness etc. are reduced. The inventor has realized thatsome materials that could be of benefit to join with each other still dohave a high carbon potential even though the alloying content and thetemperature is adapted to reduce this difference. This is for instancethe case when joining materials of different qualities, such as joininga cheaper cast iron or cast steel having high carbon content with a highcleanliness steel with low carbon content. By having a material inbetween the core part and the first material, this enable a qualitivejoin by diffusion welding of two otherwise incompatible materials.

In an embodiment of the method to form a bearing component, the firstmaterial and the core part present a carbon potential at the temperatureof joining. When joining two materials by diffusion welding it is goodif the two materials have no carbon potential, i.e. the materials haveroughly the same carbon activity, to prevent carbon from diffusing fromone material to the other. In some cases there are possibilities to finda common carbon activity between the materials by adapting the carboncontent in relation to each other and/or adapting the joiningtemperature. In some cases there are no possibilities to find a commoncarbon activity, it could be because it is not possible to adapt thetemperature due to production economic reasons, the qualities of thematerials to join are so specific that it is not possible to amend thecarbon content of them. It could also be because it simply notphysically possible to find a common carbon activity even if the abovemethods are tried, such as for instance some cast irons and highcleanliness bearing steels. It is during these circumstances when thisinventive method of including the annular part of another material isparticularly applicable with good results.

In an embodiment of the method to form a bearing component, the firstmaterial is a high cleanliness steel, such as a bearing or tool steel.Of special interest are corrosion resistant and/or wear resistantsteels. In an embodiment it is a M50 steel. In a further embodiment itis a M50NIL steel. In yet another embodiment it is any of thetraditional bearing steel as shown in ISO 683-17:1999(E) pages 9-10. Anyother steels that meet the steel cleanliness and hardness requirementsof a bearing component could be used, for instance stainless toolsteels. In a further embodiment the material used is a martensitichardenable stainless N-alloyed steel, such as XD15NW or other stainlessmartensitic hardenable steels made with good steel cleanliness. Theinvention is however not limited to these steels. The benefit of usingthese types of steel is that the portion consisting of this materialwill be very robust against wear and corrosion for instance. Hence thehigh cleanliness steel is preferably located around the highly stressedareas of the components, for instance around the raceway of a bearingring or the rolling surface of a bearing roller. It could also belocated for instance at a flange or any other portion or area of abearing component, or combinations of flange, raceways and rollingsurfaces.

In an embodiment of the method to form a bearing component, the methodis done by means of hot isostatic pressing. This comprises steps ofheating the materials pressing them against each other under specificpressure, period of time and temperature, thereby allowing the materialsto diffuse into each other. In an embodiment of the method thetemperature of joining is 1000-1300 degrees Celsius (C). In anotherembodiment of the method, the temperature of joining is 1100-1200 degreeC. In a further embodiment of the method, the temperature of joining is1140-1160 degree C., preferably 1150 degree C. But it could also be1145-1155 degree C. for instance. In an embodiment of the method thepressure is 80-310 MPa. In an embodiment of the method the time ofjoining is between 2-4 hours. This is a typical time. Shorter or longertime may be required depending on component thicknesses, such as 1-6hours.

In an embodiment of the method, the first material is in powder formbefore heating.

In an embodiment of the method to form a bearing component, the bearingcomponent is any of an inner ring, an outer ring or a roller of abearing. It could also be the rings or rollers of an axial thrust typebearing.

In an embodiment of the method to form a bearing component, at least oneof the opposing sides and the base side of the u-shaped annular part issubsequently removed from the bearing component. In a further embodimentof the method the removal of at least one of the opposing sides and thebase side of the u-shaped annular part is made by any of a subsequentgrinding step or a subsequent cutting step. This way the highcleanliness steel is revealed to form a high strength surface.

According to a third aspect, the invention presents a bearing componentformed by using the bearing component part according to the first aspectof the invention. This way the bearing component has been manufacturedin a cost efficient manner, both when it comes to the production methoditself as well as the materials used.

BRIEF DESCRIPTION OF DRAWINGS

Exemplifying embodiments will now be described more in detail withreference to accompanying drawings, as well as examples of undesirablefeatures that the invention help to prevent, wherein

FIG. 1a shows a cross section of a bearing ring made by the methodinvolving the bearing component part according to the invention;

FIG. 1b shows a cross section of a roller for a bearing made by themethod involving the bearing component part according to the invention;

FIG. 2 shows a graph illustrating two materials' carbon contentdiffusing into an intermediate material according to the invention;

FIG. 3 shows a bearing component part according to the invention;

FIG. 4 shows a bearing component part according to the invention;

FIG. 5 shows a bearing component part according to the invention havingseveral annular parts;

FIG. 6 shows a bearing component part according to the invention havingseveral annular parts;

FIG. 7 shows a bearing component part according to the invention havingseveral annular parts forming both a raceway and flanges;

FIG. 8 shows a graph illustrating an undesirable carbon content change;and

FIG. 9 shows a graph illustrating a phase fraction during theundesirable carbon content change from FIG. 8.

DETAILED DESCRIPTION OF DRAWINGS

FIG. 1a shows a cross section of a bearing component 9 joined by themethod according to the invention, bearing component 9 being a ring. Thebearing ring comprises a core part 2 and a first material 5 wherein thediffusion welding process has taken place between the core part 2 and afirst material 5, where one side of the u-shaped annular part 4 islocated. The radially and/or axially outer sides of the u-shaped annularpart 4 have been removed from the bearing component 9. The figure showsa bearing ring, where the materials are aligned along the full width ofthe component, but it could also be so that the first material 5 is onlyapplied on one or several selected portion of the bearing component 9,such as for instance a raceway or a flange (not shown in figure). Whenjoining several flanges etc made of the first material 5, severalu-shaped annular parts can be used simultaneously.

FIG. 1b shows a cross section of a bearing component 9 joined by themethod according to the invention, bearing component 9 being a roller.The bearing roller comprises a core part 2 and a first material 5wherein the diffusion welding process has taken place between the corepart 2 and a first material 5, where one side of the u-shaped annularpart 4 is located. The radially and/or axially outer sides of theu-shaped annular part 4 have been removed from the bearing component 9.The figure shows a roller where the materials are aligned along the fullwidth of the roller, but it could also be so that the first material 5is only applied on a selected portion of the roller, such as forinstance the main rolling surface or at the edges of the roller, etc.

FIG. 2 shows a graph of a desirable carbon content change according tothe invention. The change in carbon content due to the joining processcan be observed in the graph as carbon diffuses from the first material5 and the core part 2 into the material of the u-shaped annular part 4more and more as the joining process proceeds 1 t, 2 t and 3 t. Mostdiffusion occurs from the carbon rich annular part 4. The carbon contentof the first material 5 and annular part 4 in this example is almost 1and 3 wt % respectively. Here it can be clearly seen that the carboncontent have not increased dramatically at any points, which indicatesthat the carbon has not formed cementites nor more complex carbides thatcan be larger in comparison to the surrounding structure, for instance amartensitic structure, thus generally weaker than the surroundingmaterials. This would be unacceptable in high performance mechanicalcomponents, such as high quality bearing components. In this figure isshown only on material in the u-shaped annular part 4 in between thefirst material 5 and the core part 2 to be joined. There could also belayers in u-shaped annular part 4 of suitable materials known to theperson skilled in the art to achieve the results according to theprinciple of the inventive method described herein. The distance unit ofthe x-axis is not specified in this graph since it functions more as anexample describing the principle with exaggerated proportions, but atypical distance where this would occur would be 5-20 mm from thesurface of a component to be joined, for instance a from the bearingrace, and the typical thickness of the third material is in the order ofmillimeters typically 0.5 to 5 mm. Other thicknesses may be used, suchas up to 10 mm thickness.

FIG. 3 shows the bearing component part 1 intended to be used in themethod of forming a radial bearing ring according to the invention. Thecore part 2 can be seen with the u-shaped annular part 4 being attachedto and along the circumferential surface 3 of the core part 2. Theu-shaped part is attached in one of its two opposing sides 7, in thiscase the radially inner side, indicating that it is inner ring to beformed since it is attached on the ring's radially outer circumferentialsurface. The first material (5 in FIG. 4) will be filled in the space 6formed by the u-shape, the u-shape revealed as the annular part 4 isseen in a radial cross sectional view in axial direction of annular part4. The same principle would apply if it would be a roller to be formed,only the core part 2 bearing component part 1 would be solid instead ofhollow, unless it is a hollow roller that would be formed. The u-shapedcircular 4 part could also consist if different materials in itself, sothat one of the opposing sides 7 fulfills the relation that carbonactivity is greater than the carbon activity of the first material 5,meaning carbon will be diffused from the opposing side 7 of the annularpart 4 the first material resulting in a surface enrichment of carbon ofthe first material 5 to make the surface even better. I.e. one part ofthe u-shaped annular part has a material to facilitate the join ofmaterials during diffusion welding, whereas another part of the annularpart 4 comprises a material to function as a surface enrichment ofcarbon.

FIG. 4 shows the bearing component part 1 intended to be used in themethod of forming an axial thrust bearing ring according to theinvention. The core part 2 can be seen with the u-shaped annular part 4being attached to and along the circumferential surface 3 of the corepart 2. The u-shaped part is attached in its base side 8. The firstmaterial 5 has been filled in the space (6 in FIG. 3) formed by theu-shape, the u-shape revealed as the annular part 4 is seen in a radialcross sectional view in axial direction of annular part 4.

FIG. 5 shows the bearing component part 1 intended to be used in themethod of forming a bearing component (9 in FIGS. 1a and 1b ) accordingto the invention as disclosed in FIG. 3, only that several u-shapedannular parts 4 are attached to the core part 2. In this case severalu-shaped annular parts 4 are being used to form flanges.

FIG. 6 shows the bearing component part 1 intended to be used in themethod of forming a bearing component (9 in FIGS. 1a and 1b ) accordingto the invention as disclosed in FIG. 4, only that several u-shapedannular parts 4 are attached to the core part 2. In this case severalu-shaped annular parts 4 are being used to form flanges.

FIG. 7 shows the bearing component part 1 intended to be used in themethod of forming a bearing component (9 in FIGS. 1a and 1b ) accordingto the invention as disclosed in FIG. 3, only that several u-shapedannular parts 4 are used. In this case several u-shaped annular parts 4are being used to form flanges. The u-shaped annular parts 4 to formflanges are fastened to another u-shaped annular part 4 attached to thecore part 2 to form a bearing raceway. This can be useful when there isa benefit of using a raceway material and a flange material of differentqualities.

FIG. 8 shows a graph illustrating an undesirable peak 10 in carboncontent. The carbon has clearly moved from one material to the other.The carbon content clearly exceeds the carbon contents of one of thematerials of 3.5 wt % at one point reaching almost 5 wt % carbon at adepth of 20 mm from the surface of the materials to be joined, in thiscase a bearing race. The curve is un-linear. The carbon content shall bemeasured along a cross section of the joined materials, the crosssection being made perpendicular to the surface where the two materialsjoin. Having this said, the surface to be joined does by no means needto be flat, since also rounded surfaces have a perpendicular direction.

FIG. 9 shows a graph illustrating a phase fraction during theundesirable peak (5 in FIG. 7) in carbon content change from FIG. 8.From the simulations at the process temperature it can be clearly seenthat the carbon content increase that went beyond carbon content of oneof the materials in an un-linear way, has resulted in a zone where theaustenite (fcc) microstructure has increased dramatically,simultaneously as larger fraction of weaker brittle microstructurephases such as cementite (cem) networks or other complex metal carbideshas formed. Both microstructures went from being around 10% of the totalmicrostructure to around 90% at a depth off 20 mm from the surface ofthe bearing component. This may significantly reduce the strength of anyor both of the two joined materials. The cementite structure does notnecessarily have to occur during the joining as such, but the higherlevel of carbon content could react and form a weak and brittlecementite phases during a subsequent heat treatment. At a depth off 21mm from the surface of the bearing component we can see the normal facefractions of the materials at the process temperature again consistingof cementite and austenite cast iron to a large extent.

1. A bearing component part for use in a diffusion welding process,comprising: a core part presenting a first circumferential surface; andat least one annular part presenting a second circumferential surface,wherein the core part and the annular part are attached to and alongeach other in a circumferential manner through their first and secondcircumferential surfaces, wherein the at least one annular part issubstantially u-shaped in a cross sectional view, comprising twoopposing sides connected by a base side together forming a space,wherein the at least one annular part is arranged to receive a firstmaterial in the space formed by the u-shape.
 2. The bearing componentpart for according to claim 1, wherein the second circumferentialsurface of the annular part being connected to the core part, is one ofthe opposing sides of the u-shape.
 3. The bearing component part foraccording to claim 1, wherein the second circumferential surface of theannular part being connected to the core part is the base side of theu-shape.
 4. The bearing component part according to claim 1, wherein theannular part is a low carbon steel.
 5. The bearing component partaccording to claim 1, wherein the annular part is a low carbon steelhaving a carbon content of less than 0.3%.
 6. The bearing component partaccording to claim 1, wherein the annular part is a ferritic steel. 7.The bearing component part according to claim 1, wherein the annularpart is a sheet metal.
 8. The bearing component part according to claim1, wherein the thickness of the annular part is 0.5-10 mm.
 9. Thebearing component part according to claim 1, wherein the core partcomprises a cast iron.
 10. The bearing component part according to claim1, wherein the core part comprises a cast iron with a carbon content ofat least 2 wt %.
 11. The bearing component part according to claim 1,wherein the core part is a cast steel.
 12. The bearing component partaccording to claim 1, wherein the core part is a cast steel with acarbon content of 0.5 wt % or less.
 13. A method to form a bearingcomponent by means of diffusion welding, the method comprising the stepsof: providing a bearing component part, the bearing component partcomprising: a core part presenting a first circumferential surface; andat least one annular part presenting a second circumferential surface,wherein the core part and the annular part are attached to and alongeach other in a circumferential manner through their first and secondcircumferential surfaces, wherein the at least one annular part issubstantially u-shaped in a cross sectional view, comprising twoopposing sides connected by a base side together forming a space,wherein the at least one annular part is arranged to receive a firstmaterial in the space formed by the u-shape, placing a first material inthe space formed by the u-shaped annular part, sealing the space formedby the u-shaped annular part creating a closed space, performing thediffusion welding process.
 14. The method according to claim 13, whereinthe first material and the core part material presents a carbonpotential at the temperature of joining.
 15. The method according toclaim 13, wherein the first material is a high cleanliness steel. 16.The method according to claim 13, wherein the first material is any of:M50, M50 NIL, XD15NW, Bearing steel as shown in ISO 683-17:1999(E) pages9-10, Stainless tool steel, Stainless steel suitable for martensitichardening, N-alloyed stainless steel, suitable for martensitichardening, Stainless steel suitable for surface enrichment andmartensitic hardening.
 17. The method according to claim 13, wherein themethod is accomplished by hot isostatic pressing.
 18. The methodaccording to claim 13, wherein the first material is in powder formbefore heating.
 19. The method according to claim 13, wherein thebearing component is any one of: an inner ring of a bearing, an outerring of the bearing, or a roller of a roller bearing.
 20. The methodaccording to claim 13, wherein at least one of the opposing sides andthe base side of the u-shaped annular part is subsequently removed fromthe bearing component.
 21. The method according to claim 20, wherein theremoval of at least one of the opposing sides and the base side of theu-shaped annular part is made by one of: a subsequent grinding step, ora subsequent cutting step.
 22. A bearing component formed by using thebearing component part, the bearing component comprising: a core partpresenting a first circumferential surface; and at least one annularpart presenting a second circumferential surface, wherein the core partand the annular part are attached to and along each other in acircumferential manner through their first and second circumferentialsurfaces, wherein the at least one annular part is substantiallyu-shaped in a cross sectional view, comprising two opposing sidesconnected by a base side together forming a space, wherein the at leastone annular part is arranged to receive a first material in the spaceformed by the u-shape.